Bone cement mixing apparatus having improved mixing blade configuration

ABSTRACT

A bone cement mixing device has a canister which is modular in design and constructed from a transparent material. The mixing device further has a mixing head assembly having a crank that is operatively coupled to a mixing blade via a gear train. The gear train is configured to drive the mixing blade in a reciprocating manner including the varying of the angular velocity, direction of travel, and angular distance of travel of the blade while the crank is rotated at a constant velocity and direction. The mixing blade has a fluid passage defined therein which allows the liquid cement component to be delivered at various locations within the mixing chamber of the canister. A method of mixing bone cement is also disclosed.

PROVISIONAL PATENT APPLICATION

[0001] This application claims the benefit of U.S. ProvisionalApplication Serial No. 60/250,808, filed Dec. 1, 2000. The disclosure ofthe above-identified provisional patent application is hereby totallyincorporated by reference in its entirety.

CROSS REFERENCE

[0002] Cross reference is made to copending U.S. utility patentapplication Ser. No. ______ (Attorney Docket No. 1671-0206), entitled“Bone Cement Mixing Apparatus having Improved Gearing Arrangement forDriving a Mixing Blade” by Timothy G. Vendrely, Jack F. Long,Christopher Battles, Paul DeCesare, Patrick Gutelius, and Sam Sackettwhich is assigned to the same assignee as the present invention andwhich is filed concurrently herewith. The disclosure of theabove-identified utility patent application is hereby totallyincorporated by reference in its entirety.

TECHNICAL FIELD OF THE INVENTION

[0003] The present invention relates generally to a surgical assembly,and more particularly to an apparatus and method for mixing bone cement.

BACKGROUND OF THE INVENTION

[0004] It is necessary in many orthopedic surgical procedures to employa cement or grouting type agent, such as for attaching artificial jointimplants, repairing or forming joints in bones, or other forms oforthopedic work. The type of cement generally used for these purposes isa self-curing resin formed from the blending of a wide variety of liquidmonomers or comonomers with powdered polymers or copolymers to form aviscous admixture to be used as the grouting agent.

[0005] The admixture of the powder and liquid components develops aquick setting material. As such, preparation of the cement usuallyoccurs directly within the operating area just prior to use. Inparticular, a bone cement mixing apparatus is generally utilized to mixthe powder and liquid components in the operating area. The resultantadmixture is then removed from the mixing apparatus and placed in acement delivery apparatus for subsequent use by the surgeon.Specifically, the bone cement must generally first be scooped orotherwise removed from the mixing apparatus and thereafter placed in asyringe-type delivery apparatus for use by the surgeon.

[0006] The aforedescribed system for mixing and delivering bone cementhas a number of drawbacks associated therewith. For example, monomervapors are generated during the depositing of the monomer into themixing apparatus and during the subsequent mixing of the monomer withthe powder component of the bone cement. Such monomer vapors may benoxious and/or toxic. Because the bone cement is generally mixed in theoperating room environment, it is important to prevent any monomer orits vapors from escaping the mixing apparatus. However, heretoforedesigned mixing apparatus have not included mechanisms for controllingthe escape of such vapors.

[0007] Moreover, heretofore designed mixing apparatus have been plaguedwith problems relating to the incomplete mixing of the liquid componentand the powder component. Specifically, the powder component and liquidcomponent are often inadequately mixed during operation of heretoforedesigned systems. Such a problem is further compounded by the fact thatheretofore designed mixing vessels are not transparent therebypreventing the contents of the vessel (i.e. the bone cement) from beingviewed by the operator of the mixing apparatus.

[0008] In addition, the aforedescribed system also suffers fromoperational inefficiencies relating to the need to transfer the mixedbone cement from the mixing apparatus to the delivery apparatus.Specifically, the need to remove the mixed bone cement from one device(i.e. the mixing apparatus) and place it in a second device (i.e. thedelivery device) creates an extra step in the process thereby increasingthe time necessary to deliver the mixed bone cement. Moreover, aquantity of the bone cement is lost in the process since it is highlyunlikely that all of the mixed cement is actually removed from themixing apparatus and placed in the delivery apparatus.

[0009] What is needed therefore is an apparatus and method for mixing abone cement which overcomes one or more of the above-mentioneddrawbacks. What is particularly needed is an apparatus and method formixing bone cement which reduces, if not eliminates, exposure to vaporsfrom the liquid bone cement component within the operating area. What isfurther needed is an apparatus and method for mixing bone cement whichmay also be utilized to delivery the mixed bone cement. What is moreoverneeded is an apparatus and method for mixing bone cement which reduces,or even eliminates, the occasions in which a portion of the powdercement component is not thoroughly mixed with the liquid cementcomponent.

SUMMARY OF THE INVENTION

[0010] In accordance with the concepts of the present invention, thereis provided a bone cement mixing apparatus. The bone cement mixingapparatus includes a handle, and a canister defining a mixing chamber.The bone cement mixing apparatus further includes a mixing blade whichis caused to rotate in response to movement of the handle, the mixingblade being positioned within the mixing chamber. The mixing bladeincludes a shaft and at least one vane supported by the shaft. Also, theshaft has defined therein (i) an inlet orifice, (ii) a plurality ofoutlet orifices, and (iii) a passageway which places the inlet orificein fluid communication with each of the plurality of outlet orifices.

[0011] Pursuant to another embodiment of the present invention, there isprovided a method of mixing bone cement. The method includes the step of(i) placing a powder bone cement component within a canister, (ii)sealing the canister after the placing step, (iii) advancing a liquidbone cement component through a mixing blade located within the canisterafter the sealing step, and (iv) rotating the mixing blade after theliquid bone cement component is advanced through the mixing blade. Themixing blade includes (i) an inlet orifice, (ii) a plurality of outletorifices, and (iii) a passageway which places the inlet orifice in fluidcommunication with each of the plurality of outlet orifices. Inaddition, the advancing step includes the step of advancing the liquidbone cement component (i) into the mixing blade through the inletorifice, (ii) through the passageway, and (iii) out of the mixing bladethrough the plurality of outlet orifices.

[0012] Yet according to another embodiment of the present invention,there is provided a bone cement mixing apparatus. The bone cement mixingapparatus includes a container defining a mixing chamber. Further, thebone cement mixing apparatus includes a mixing blade positioned withinthe mixing chamber, the mixing blade defining (i) an inlet orifice, (ii)a plurality of outlet orifices, and (iii) a passageway which places theinlet orifice in fluid communication with each of the plurality ofoutlet orifices.

[0013] Yet according to another embodiment of the present invention,there is provided a bone cement mixing apparatus which includes ahandle. The bone cement mixing apparatus further includes a firstcanister segment defining a first mixing chamber portion, and a secondcanister segment defining a second mixing chamber portion. Also, thebone cement mixing apparatus includes a mixing blade which is caused torotate in response to movement of the handle. The mixing blade islocated within both the first mixing chamber portion and the secondmixing chamber portion. Moreover, the first canister segment includes afirst coupling, and the second canister segment includes a secondcoupling. The first coupling cooperates with the second coupling so asto secure the first canister segment to the second canister segment.

[0014] It is therefore an object of the present invention to provide anew and useful apparatus for mixing bone cement.

[0015] It is moreover an object of the present invention to provide animproved apparatus for mixing bone cement.

[0016] It is a further object of the present invention to provide a newand useful method for mixing bone cement.

[0017] It is also an object of the present invention to provide animproved method for mixing bone cement.

[0018] It is yet another object of the present invention to provide anapparatus and method for mixing bone cement which reduces, if noteliminates, exposure to vapors from the liquid bone cement componentwithin the operating area.

[0019] It is moreover an object of the present invention to provide anapparatus and method for mixing bone cement which may also be utilizedto delivery the mixed bone cement.

[0020] It is a further object of the present invention to provide anapparatus and method for mixing bone cement which reduces, or eveneliminates, the occasions in which a portion of the powder cementcomponent is not thoroughly mixed with the liquid cement component.

[0021] The above and other objects, features, and advantages of thepresent invention will become apparent from the following descriptionand the attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0022]FIG. 1 is a perspective view of bone cement mixing device whichincorporates the features of the present invention therein;

[0023] FIGS. 2-5 are side elevational views of the mixing device of FIG.1;

[0024]FIG. 6 is an enlarged plan view of the mixing device of FIG. 1;

[0025]FIG. 7 is a cross sectional view of the mixing device of FIG. 1,taken along the line 7-7 of FIG. 5, as viewed in the direction of thearrows;

[0026]FIG. 8 is a cross sectional view taken along the line 8-8 of FIG.3, as viewed in the direction of the arrows;

[0027]FIG. 9 is a cross sectional view taken along the line 9-9 of FIG.2, as viewed in the direction of the arrows;

[0028]FIG. 10 is a cross sectional view taken along the line 10-10 ofFIG. 4, as viewed in the direction of the arrows;

[0029]FIG. 11 is a cross sectional view taken along the line 11-11 ofFIG. 4, as viewed in the direction of the arrows;

[0030] FIGS. 12-14 are exploded perspective views of the mixing headassembly of the mixing device of FIG. 1;

[0031]FIGS. 15 and 16 are bottom perspective views of the gear train ofthe mixing head assembly of FIGS. 12-14;

[0032]FIG. 17 is a bottom perspective view of the directional gear ofthe gear train of FIGS. 15 and 16;

[0033] FIGS. 18-20 are fragmentary perspective views which show theblade wiping diaphragm of the mixing device of FIG. 1

[0034]FIG. 21 is fragmentary plan view of the blade wiping diaphragm ofFIGS. 18-20 and the mixing blade of FIG. 7;

[0035]FIG. 22 is a fragmentary side elevational view of the blade wipingdiaphragm of FIGS. 18-20 and the mixing blade of FIG. 7;

[0036]FIGS. 23 and 24 are fragmentary perspective views of the mixingdevice of FIG. 1 with the cement delivery nozzle secured thereto; and

[0037]FIG. 25 is an enlarged view of the cement delivery nozzle of FIGS.23 and 24.

DETAILED DESCRIPTION OF THE INVENTION

[0038] While the invention is susceptible to various modifications andalternative forms, a specific embodiment thereof has been shown by wayof example in the drawings and will herein be described in detail. Itshould be understood, however, that there is no intent to limit theinvention to the particular form disclosed, but on the contrary, theintention is to cover all modifications, equivalents, and alternativesfalling within the spirit and scope of the invention.

[0039] Referring now to FIGS. 1-7, there is shown a bone cement mixingdevice 10 which incorporates the features of the present inventiontherein. As shall be discussed below in greater detail, the bone cementmixing device 10 of the present invention is configured to receive aquantity of a powder bone cement component and a liquid bone cementcomponent (e.g. a monomer) and thereafter mix the powder component andliquid component together. The bone cement mixing device 10 is alsooperable as a bone cement delivery device thereby eliminating the needto utilize a separate delivery device.

[0040] The mixing device 10 includes a canister 12 having a mixingchamber 14 defined therein. The canister 12 is preferably embodied as apair of identical cylindrically-shaped cartridges 16, 18. Use of thecartridges 16, 18 allows for modular construction of the mixing device10 while also reducing the number of different components which areutilized in the design thereof.

[0041] Each of the cartridges 16, 18 is preferably constructed of atransparent material such as a transparent plastic material. Such use ofa transparent material in the construction of the cartridges 16, 18 isadvantageous in that the operator the mixing device may visually observethe contents within the mixing chamber 14 (i.e. the powder and liquidcement components) in order to visually determine if the components havebeen adequately (i.e. thoroughly) mixed with one another.

[0042] Moreover, the cartridges 16, 18 may be constructed to accommodateany quantity of bone cement. Preferably, the cartridges 16, 18 areconstructed to hold and mix at least 120 grams of powder bone cementcomponent and the associated quantity of the liquid bone cementcomponent (i.e. the monomer). Such a configuration is advantageous inthat surgical procedures commonly require the preparation of three (3)batches of bone cement powder (with each batch being 40 grams). It isoften necessary when using a heretofore designed mixing apparatus foreach of the three batches to be prepared (i.e. mixed) separately therebypotentially creating delays and/or timing difficulties within theoperating area during a surgical procedure. However, the mixing device10 of the present invention overcomes this limitation by beingconfigured to mix all three of the batches simultaneously.

[0043] The upper end 20 of each of the cartridges 16, 18 has a firstnumber of threads 22 defined therein, whereas the lower end 24 of eachof the cartridges 16, 18 has a corresponding number of threads 26defined therein. The threads 22, 26 may be threadingly engaged with oneanother (as in the case of the junction between the cartridges 16, 18),or may be engaged to a number of other components. In particular, asshown in FIG. 7, the threads 22 of the upper end 20 of the cartridge 16are threadingly engaged with a number of threads 28 associated with amixing head assembly 30. The threads 26 of the lower end 24 of thecanister 18, on the other hand, are threadingly engaged with a number ofthreads 32 defined in a base 34. It should be appreciated that sealingmembers such as O-rings 158 (see FIGS. 7, 9, and 23) are preferablyutilized at each threaded coupling (i.e. between the cartridges 16, 18,between the cartridge 16 and the mixing head assembly 30, and betweenthe cartridge 18 and the base 34)

[0044] As shown in FIGS. 1, 7, and 9, the mixing head assembly 30includes an upper gear housing 36 and a lower gear housing 38. The uppergear housing 36 is press fit or otherwise secured to the lower gearhousing 38. The mixing head assembly 30 also includes a crank 40 whichis rotatably secured to the upper gear housing 36. The crank 40 includesan elongated arm 42 having a knob 44 rotatably secured to an endthereof. As will be discussed below in greater detail, the upper gearhousing 36 and the lower gear housing 38 cooperate to house a gear train46 which is driven by rotation of the crank 40. Specifically, the geartrain 46 includes an output pinion 48 which is rotatably coupled to thelower gear housing 38. The output pinion 48 includes a downwardlyextending coupling portion 50 which extends through an aperture 51defined in the lower gear housing 38 (see also FIG. 13). The couplingportion 50 of the output pinion 48 is non-rotatably secured to an upperend 106 of a mixing blade 52. In particular, as shown in FIGS. 9 and 12,the coupling portion 50 of the output pinion 48 includes a number ofbarbs 58 which are received into a corresponding number of slots 60 (seeFIGS. 7 and 9) defined in a coupling portion 108 of the mixing blade 52.Hence, rotation of the output pinion 48 causes similar rotation (i.e. inthe same direction and at the same angular velocity) of the mixing blade52.

[0045] Referring now to FIGS. 12-17, the mixing head assembly 30 isshown in greater detail. In addition to the crank 40 and the gearhousings 36, 38, the mixing head assembly 30 also includes a directionalgear 54, an idler gear 56, and the output pinion 48. As shown in FIGS.12 and 13, the directional gear 54, the idler gear 56, and the outputpinion 48 are housed within the housing defined by the upper gearhousing 36 and the lower gear housing 38. Specifically, the outputpinion 48 has a shoulder 60 defined therein. Upon insertion of thecoupling portion 50 of the output pinion 48 into the aperture 51 definedin the lower gear housing 38, the shoulder 60 of the output pinion 48contacts a retaining surface 62 of the gear housing 38 (see FIG. 13)thereby retaining the output opinion 48 while also allowing it to rotaterelative to the gear housing 38.

[0046] The idler gear 56 has an aperture 64 defined therein (see FIG.12) which is received around a post 66 (see FIGS. 13 and 14) defined inthe lower gear housing 38 thereby rotatably securing the idler gear 56to the lower gear housing 38. The other end of the idler gear 56 has apost 68 extending therefrom which is received into a slot 70 defined inthe body 72 of the directional gear 54 (see FIGS. 10 and 17). The post68 is captured by or is otherwise retained within the slot 70 duringrotation of the directional gear 54.

[0047] The directional gear 54 is non-rotatably secured to the crank 40by use of a hexagonally-shaped coupling mechanism 74. In particular, thecrank 40 has a hexagonally-shaped member 76 extending downwardlytherefrom, whereas the body 72 of the directional gear 54 has a slightlylarger hexagonally-shaped member 78 extending upwardly therefrom. Duringassembly of the mixing head assembly 30, a shoulder 80 of the crank ispositioned in contact which a bearing surface 82 defined on the uppersurface of the upper gear housing 36 (see FIG. 13) thereby allowing thehexagonally-shaped member 76 of the crank 40 to extend through a housingopening 84 defined in the upper gear housing 36. When positioned in sucha manner, the hexagonally-shaped member 76 of the crank 40 may be pressfit or otherwise received into the hexagonally-shaped member 78 of thedirectional gear 54 which is positioned within the upper gear housing 36(see FIG. 11). When secured in such a manner, rotation of the crank 40relative to the upper gear housing 36 causes similar rotation of thedirectional gear 54 relative to the upper gear housing 36. Note that thedirectional gear 54 is caused to rotate about a central axis CA as shownin FIG. 17.

[0048] The idler gear 56 is meshingly engaged with both the directionalgear 54 and the output pinion 48. In particular, as shown in FIG. 17,the directional gear 54 includes a first number of gear teeth 86 definedin the body 72 thereof. The gear teeth 86 are positioned around aportion of the periphery of an aperture 88 which defines the axis ofrotation of the directional gear 54. The directional gear 54 alsoincludes a second number of gear teeth 90 defined in the body 72thereof. As can be seen in FIG. 17, the gear teeth 90 are spacedradially outwardly from the gear teeth 86. As will be discussed below ingreater detail, the gear teeth 86 and the gear teeth 90 selectivelymeshingly engage with the idler gear 56 so as to selectively drive theoutput pinion 48 (and hence the mixing blade 52) at varying velocitiesand directions of rotation.

[0049] Note that the central axis CA lies in a plane P which divides thedirectional gear 54 into a first directional gear side and a seconddirectional gear side (see e.g. FIG. 17). Moreover, the directional gear54 is configured so that (i) the gear teeth 86 are positioned entirelyon the first input gear side, and (ii) the gear teeth 90 are positionedentirely on the second input gear side as shown in FIG. 17.

[0050] As shown in FIGS. 12-14, 15, and 16, the idler gear 56 has anumber of gear teeth 92 defined therein, whereas the output pinion 48has a number of gear teeth 94 defined therein. The gear teeth 92 of theidler gear 56 are meshingly engaged with the gear teeth 94 of the outputpinion 48. As such, rotation of the idler gear 56 in a given directioncauses rotation of the output pinion 48 in the opposite direction. Forexample, clockwise rotation of the idler gear 56 causes counterclockwiserotation of the output pinion 48, and vice versa.

[0051] As alluded to above, the gear teeth 92 of the idler gear 56 areengaged by either the inner gear teeth 86 or the outer gear teeth 90 ofthe directional gear 54 during rotation of the directional gear 54.Specifically, during rotation of the directional gear 54 in thecounterclockwise direction (as viewed from the bottom perspective viewof FIGS. 15-17 and designated by the arrow 96), the idler gear 56 isinitially engaged by the outer gear teeth 90 of the directional gear 54thereby causing the idler gear 56 to likewise be rotated in thecounterclockwise direction (as indicated by the arrow 96). Rotation ofthe idler gear 56 in the counterclockwise direction causes rotation ofthe output pinion 48 (and hence the mixing blade 52) in the oppositedirection (i.e. in a clockwise rotation as viewed from the bottomperspective view of FIGS. 15-17 and designated by the arrow 98).

[0052] Continued rotation of the crank 40 (and hence the directionalgear 54) in the counterclockwise direction (as viewed from the bottomperspective view of FIGS. 15-17 and indicated by the arrow 96) causesthe last gear tooth 100 of the outer gear teeth 90 to be rotated out ofengagement with the idler gear 56 and a first tooth 102 of the innergear teeth 86 to be rotated into meshing engagement with the idler gear56. It should be appreciated that a small radial gap may be providedbetween the last gear tooth 100 of the outer gear teeth 90 and the firstgear tooth 102 of the inner gear teeth 86 in order to prevent the idlergear 56 from being simultaneously engaged by both sets of gear teeth 86,90.

[0053] In any event, as the inner gear teeth 94 meshingly engage theidler gear 56, the direction of travel of the idler gear 56 is changed.Specifically, when the directional gear 54 is rotated in thecounterclockwise direction (as viewed from the bottom perspective viewof FIGS. 15-17 and indicated by the arrow 96), meshing engagement withthe inner gear teeth 94 causes the idler gear 56 to be rotated in theopposite direction (i.e. the clockwise direction as viewed from thebottom perspective view of FIGS. 15-17 and indicated by the arrow 94).Such clockwise rotation of the idler gear 56 causes the output pinion 48(and hence the mixing blade 52) to be rotated in the opposite direction(i.e. the counterclockwise direction as viewed from the bottomperspective view of FIGS. 15-17 and indicated by the arrow 96).

[0054] It should be appreciated that if the crank 40 is rotated in theopposite direction (i.e. so as to cause rotation of the directional gear54 in the clockwise direction as viewed in FIGS. 15-17 and indicated byarrow 98), the idler gear 56 and the output pinion 48 are rotated in therespective opposite directions to that as described above. Inparticular, rotation of the directional gear 54 in the clockwisedirection (i.e. in the direction of arrow 98 of FIGS. 15-17) causes (1)clockwise rotation of the idler gear 56, and (2) counterclockwiserotation of the output pinion 48 (and hence the mixing blade 52) whenthe idler gear 56 is meshingly engaged with the outer gear teeth 90.Similarly, rotation of the directional gear 54 in the clockwisedirection (i.e. in the direction of arrow 98 of FIGS. 15-17) causes (1)counterclockwise rotation of the idler gear 56, and (2) clockwiserotation of the output pinion 48 (and hence the mixing blade 52) whenthe idler gear 56 is meshingly engaged with the inner gear teeth 86.

[0055] Hence, as described above, the gear train 46 of the presentinvention is configured such that the direction of rotation of theoutput pinion 48 changes despite rotation of the crank 40 in only asingle direction. Specifically, as the idler gear 56 is engaged with theouter gear teeth 90, the output pinion 48 and hence the mixing blade 52is rotated in a first direction. However, as the idler gear 56disengages the outer gear teeth 90 and engages the inner gear teeth 86,the direction of travel of the output pinion 48 and hence the mixingblade 52 is reversed thereby creating alternating or reciprocatingmotion.

[0056] Moreover, since the relatively large number of individual gearteeth associated with the outer gear teeth 90 creates a relatively largegear ratio with the idler gear 56 relative to the gear ratio created byinner gear teeth 86 and the idler gear 56, varying angular distances oftravel and speeds of the mixing blade 52 are created. Specifically, therelatively high gear ratio created by the outer gear teeth 90 causes theoutput pinion 48 to be driven across a greater angular distance when theidler gear 56 is engaged with the outer gear teeth 90 relative to theangular distance across which the output pinion 48 is driven when theidler gear 56 is engaged with the inner gear teeth 86. In one exemplaryembodiment, the output pinion 48 (and hence the mixing blade 52) isdriven across 540° of rotation when the idler gear 56 is engaged withthe outer drive teeth 90, whereas the output pinion (and hence themixing blade 52) is only advanced across 135° of rotation (in theopposite direction) when the idler gear 56 is engaged with the innerdrive teeth 86. In other words, in such an exemplary embodiment, when anoperator advances the crank 40 through an entire revolution (i.e. 360°of rotation), the mixing blade 52 is driven across 540° of rotation in afirst direction and then reversed and driven across 135° of rotation inthe opposite direction.

[0057] Moreover, the relatively high gear ratio created by the outergear teeth 90 also causes the output pinion 48 to be driven at a greaterangular velocity when the idler gear 56 is engaged with the outer gearteeth 90 relative to the angular velocity at which the output pinion 48is driven when the idler gear 56 is engaged with the inner gear teeth86. In one exemplary embodiment, when the idler gear 56 is engaged withthe outer drive teeth 90, the output pinion 48 (and hence the mixingblade 52) is driven at a velocity which is approximately three timesgreater than the velocity at which the output pinion 48 (and hence themixing blade 52) is driven when the idler gear 56 is engaged with theinner drive teeth 86. In other words, in such an exemplary embodiment,when an operator advances the crank 40 through an entire revolution(i.e. 360° of rotation), the mixing blade 52 is driven three times asquickly in the first direction as it is when reversed and driven in theopposite direction.

[0058] It should be appreciated that the configuration of thedirectional gear 54 described herein is exemplary in nature and may bealtered to fit the requirements of a given design of the mixing device10. In particular, it should be noted that the number of teeth includedin the gear teeth 86 and 90 may be varied in order to produce a desiredgear ratio. Such modification to the gear teeth 86 and 90 would allowfor modification to the angular distance and speed at which the mixingblade 52 is driven during rotation of the crank 40 by the operator.

[0059] It should also be appreciated that the aforedescribed drivecharacteristics of the mixing head assembly 30 provide numerousadvantages to the mixing device 10 of the present invention relative toheretofore designed mixing devices. For example, the aforedescribedreciprocating movement of the mixing blade 52 (i.e. at varying angulardistances and speeds) creates desirable “agitation” within the mixingchamber 14 of the canister 12. Such agitation increases the mix qualityof the mixing device 10 by reducing, if not eliminating, the amount ofthe powder component which is not thoroughly mixed with the liquidcomponent.

[0060] Referring now to FIG. 7, the mixing blade 52 will be described ingreater detail. The mixing blade 52 includes an elongated central shaft104 having an upper end 106 which includes the coupling portion 108 forsecuring the shaft 104 of the blade 52 to the coupling portion 50 of theoutput pinion 48. The shaft 104 also has a lower end 108 which extendsdownwardly and into contact with a plunger 110. The plunger 110 is madefrom a plastic material such as polyethylene. The plunger 110 includes arecess 112 which receives a tip 114 of the shaft 104 thereby providingmechanical support for the shaft 104 during rotation thereof.

[0061] A number of blades or vanes 116 extend outwardly from the shaft104 as shown in FIG. 7. The mixing blade 52 may be configured as a“two-dimensional” (i.e. flat) blade, or alternatively, may be configuredas a “three dimensional” blade. Specifically, although the vanes 116 maybe configured to extend outwardly in only two directions from the shaft104, the vanes 116 of the mixing blade 52 may also be configured toextend outwardly from the shaft 104 in three directions. In such a threedimensional configuration, the mixing blade 52 is not substantially flatwhen positioned on a relatively flat surface, but rather extends in anumber of different directions (including upwardly) from the flatsurface.

[0062] Moreover, as shown in FIG. 7, the vanes 116 are oriented insomewhat of a helical configuration around the shaft 104. Such aconfiguration provides numerous advantages to the mixing device 10 ofthe present invention. For example, the helical configuration of themixing blade 52 generates a desirable amount of “turbulence” within themixing chamber 14 of the canister 12 thereby increasing the mixingefficiency of the mixing device 10.

[0063] The shaft 104 of the mixing blade 52 has an elongated fluidpassageway 118 defined therein. The fluid passageway 118 extends fromthe upper end 106 of the shaft 104 to the lower end 108 of the shaft104. The fluid passageway 118 is placed in fluid communication with themixing chamber 14 of the canister 12 via a number of fluid orifices 120defined in the shaft 104. While seven (7) fluid orifices 120 are showndefined in the shaft 104, it should be appreciated that there may bemore than seven (7) fluid orifices defined in the shaft 104 (e.g. nineor ten fluid orifices). Alternatively, there may be less than seven (7)fluid orifices defined in the shaft 104 (e.g. two or three fluidorifices). The fluid passageway 118 and the fluid orifices 120 allow forthe introduction of the liquid cement component (e.g. the monomer)without exposing the operator to any vapors or fumes from therefrom. Inparticular, as shown in FIG. 7, the crank 40 has a monomer delivery port122 defined therein (see also FIG. 12). A tube 124 (see FIG. 7) is pressfit into the lower end of the delivery port 122 and extends downwardlythrough the aperture 88 defined in the directional gear 54 and a similaraperture 126 defined in the output pinion 48 (see FIGS. 9, 12, 15, and16). The lower end of the tube 124 is press fit or otherwise positionedin the coupling portion 108 of the mixing blade 52 so as to be in fluidcommunication with the fluid passageway 118 defined in the shaft 104.

[0064] Hence, a quantity of liquid cement component may be introducedinto the mixing chamber 14 of the canister 12 through the delivery port122. Specifically, the liquid cement component (e.g. the monomer) may beintroduced into the mixing chamber 14 via a fluid path which includesthe delivery port 122, the tube 124, the fluid passageway 118 of theshaft 104, and the fluid orifices 120 of the shaft 104. In such amanner, the monomer may be delivered at various locations throughout thedepth of the powder component which is present in the mixing chamber 14.In particular, since the fluid orifices 120 are provided at a number ofdifferent locations along the length of the shaft 104, the liquidcomponent (e.g. the monomer) is delivered at locations throughout theheight of the canister 12 thereby allowing the liquid to be interspersedthroughout the powder component present in the mixing chamber 12. Thisis a significant advantage over heretofore designed systems in which themonomer is poured or otherwise advanced through the lid of the mixingapparatus thereby only allowing the monomer to be introduced to the“top” of the powder within the mixing apparatus. Moreover, the structureof the present invention also provide advantages over heretoforedesigned systems having a delivery path through the mixing shaft of thesystem which have an opening only at the bottom end of the shaft(similar to a common drinking straw). In such a configuration, themonomer flows only out of the bottom of the shaft and in some cases maybe restricted by the plunger on which the lower end of the shaft rests.

[0065] It should be appreciated that the monomer delivery port 122 maybe embodied to include a luer lock that is configured such that a lueror similar spout from a monomer delivery device (not shown) may beextended into sealing engagement therewith. The use of such a luer lockallows monomer to be dispensed into tube 124 (and hence the mixingchamber 14 of the canister 12) while preventing monomer vapors fromescaping between the monomer delivery device and the mixing device 10(i.e. between luer of the delivery device and the luer lock of themixing device).

[0066] It should be appreciated that such a luer lock may be configuredto facilitate a “slip fit” type of sealing arrangement, or, alternately,may be configured to facilitate a threaded coupling with thecorresponding mechanism of the monomer delivery device. Moreover, acombination coupling mechanism may be utilized which facilitates matingwith both threaded and non-threaded couplings.

[0067] A cap 128 is provided to selectively seal the delivery port 122.Specifically, the cap 128 may be sealing received into the delivery port122 in order to seal the delivery port 122 in a manner which preventsvapors or the like from escaping therefrom. A tether 130 extends betweenthe crank 40 and the cap 128 in order to movably secure the cap 128 tothe crank 40.

[0068] As alluded to above, the cap 128 is used to seal delivery port122 after the monomer has been dispensed into mixing chamber 14 duringthe mixing process. The cap 128 is shown in a disengaged position inFIG. 7 in anticipation of the coupling of the monomer delivery device(not shown) with the delivery port 122 for the purpose of deliveringmonomer from the monomer delivery device into the mixing chamber 14. Itwill be appreciated that a variety of luer locks and luer lock caps maybe used in the present invention. For example, a self-closing luer lockmay be used thereby eliminating the need for luer cap 128 or, asdescribed above, a threaded luer lock may be used to screw the cap 128onto the body of the crank 40. In another embodiment, the monomerdelivery device itself may be used as a seal for the luer lock. In yetanother embodiment, the luer cap 128 may be replaced with a paper-backedpiece of re-sealable tape or the like which may be removed to allow formating with the monomer delivery device, and then replaced when themonomer delivery device is detached.

[0069] Referring now to FIG. 9, the lower gear housing 38 has a vacuumport 132 defined therein (see also FIG. 1). A vacuum source (not shown)may be fluidly coupled to the vacuum port 132 in order to draw air fromthe mixing chamber 14 of the mixing device 10. The introduction of avacuum is useful during the aforedescribed introduction of the liquidcement component into the mixing chamber 14 since the presence of lowerpressure within the chamber 14 tends to draw the liquid (i.e. themonomer) through the fluid orifices 120 of the shaft 104 and into themixing chamber 14. Moreover, the presence of the vacuum also removesvapors and the like from the mixing device 10 thereby further reducingthe occasions in which such vapors escape from the device 10.

[0070] As shown in FIG. 7, 9, 18-22, the mixing device 10 also includesa blade wiping member or diaphragm 134. The blade wiping diaphragm 134is preferably constructed of an elastomeric material. The blade wipingdiaphragm 134 has a number of vane receiving slots 136 and a shaftreceiving opening 138 defined therein. As will now be described ingreater detail, the blade wiping diaphragm 134 is provided to “wipe” orotherwise remove residual bone cement for the mixing blade 52 duringremoval thereof from the mixing chamber 14. As such, the blade wipingdiaphragm 134 may be configured to include any number, size, or shape ofvane receiving slots 136 in order to accommodate a given design of amixing blade 52.

[0071] Once the liquid bone cement component (e.g. the monomer) and thepowder bone cement component have been thoroughly mixed with oneanother, the lower gear housing 38 is unscrewed from the cartridge 16 sothat the mixing head assembly 30 may be removed from the cartridge 16thereby allowing a delivery nozzle assembly 150 (see FIGS. 23 and 24) tobe screwed onto the cartridge 16 in its place. During such removal ofthe mixing head assembly 30, as shown in FIG. 19, the vanes 116 of themixing blade 52 are advanced through the vane receiving slots 136 of theblade wiping diaphragm 134. Such advancement of the vanes 116 throughthe vane receiving slots 136 wipes or otherwise removes any residualbone cement from the vanes 116 thereby preventing such residual bonecement from being wasted (i.e. removed from the mixing chamber 14, butnot utilized in the surgical procedure).

[0072] In order to provide for proper alignment of the vanes 116 of themixing blade 52 with the vane receiving slots 136, the blade wipingdiaphragm 134 is rotatably secured to the cartridge 16. In particular,as show in FIG. 18, the cartridge 16 includes a number of retainingmembers or snaps 140. An outer peripheral edge 142 of the blade wipingdiaphragm 134 is positioned under the snaps 140 in order to secure thediaphragm 134 to the cartridge 16 during securement of the mixing headassembly 30 to the cartridge 16. Moreover, the mixing blade 52 ispreferably configured to include a number of protrusions or “wings” 144which extend outwardly from the shaft 104 (see FIGS. 21 and 22). Thewings 144 are aligned with the vanes 116 and are therefore positioned inthe vane receiving slots 136 as shown in FIGS. 21 and 22. As such,rotation of the mixing blade 52, and therefore the wings 144, causessimilar rotation of the blade wiping diaphragm 134.

[0073] Moreover, the wings 144 also function to retain the blade wipingdiaphragm 134 on the mixing blade 52 prior to securement of the mixinghead assembly 30 to the cartridge 16. In particular, the blade wipingdiaphragm 134 is initially secured to the wings 144 of the mixing blade52 prior to use of the mixing device 10. In such a manner, as shall bediscussed below in greater detail, the powder bone cement component maybe poured or otherwise advanced into the open end (i.e. the upper end20) of the cartridge 16. Once the powder component has been poured intothe open end of the cartridge 16, the mixing head assembly 30 is screwedonto the threads 22 of the upper end 20 of the cartridge 16. As themixing head is screwed onto the upper end 20 of the cartridge 16, theouter peripheral edge 142 of the blade wiping diaphragm 134 is pressedor otherwise advanced under each of the snaps 140 in order to secure thediaphragm 134 to the cartridge 16. As shall be discussed below ingreater detail, such positioning of the outer peripheral edge 142 of theblade wiping diaphragm 134 under the snaps 140 allows for retention ofthe blade wiping diaphragm 134 during subsequent removal of the mixinghead assembly 30.

[0074] It should be appreciated that the configuration of the mixingdevice 10 in which the blade wiping diaphragm 134 is rotated in concertwith the mixing blade 52 reduces the number of vane receiving slots 136that must be included in the construction of the blade wiping diaphragm134. Specifically, since the wings 144 are retained in the slots 136,the vanes 116 (which are aligned with the wings 144) are likewise at alltimes aligned with the vane receiving slots 136. Hence, at any giventime, the mixing blade 52 may be removed by pulling the vanes 116 of theblade 52 through the vane receiving slots 136. Such a reduction in thenumber of vane receiving slots 136 facilitates ease of manufacture ofthe blade wiping diaphragm 134.

[0075] As shown in FIG. 22, the shaft 104 of the mixing blade 52 alsohas an upper shoulder 146 and a lower shoulder 148 defined therein. Asshown in FIG. 22, the body of blade wiping diaphragm 134 is captured orotherwise positioned between the upper shoulder 146 and the lowershoulder 148. The upper shoulder 146 is greater in diameter than thelower shoulder 148. The upper shoulder prevents upward movement of theblade wiping diaphragm 134. The lower shoulder 148, on the other hand,is somewhat smaller in diameter and includes a number of rounded edges.In such a manner, the lower shoulder 148 supports the blade wipingdiaphragm 134 in its desired position, but also allows for removal ofthe mixing blade 52 since the lower shoulder may be advance through theshaft receiving opening 138 of the blade wiping diaphragm 134 duringremoval of the blade 52.

[0076] As alluded to above, once the liquid cement component and thepowder cement component have been thoroughly mixed, the mixing device 10of the present invention may be utilized to deliver the mixed bonecement. In particular, as shown in FIGS. 23-25, once the liquid bonecement component (e.g. the monomer) and the powder bone cement componenthave been thoroughly mixed with one another, the lower gear housing 38is unscrewed from the cartridge 16 so that the mixing head assembly 30may be removed from the cartridge 16. Thereafter, the delivery nozzleassembly 150 may be screwed onto the threads 22 of the upper end 20 ofthe cartridge 16. The nozzle assembly 150 includes a nozzle 152 and anelongated tube 154. It should be appreciated that the length and/ordiameter of the elongated tube 154 may be varied in order to fit therequirements of a given delivery application. Moreover, it should alsobe noted that in certain situations, it may be desirable to dispense(i.e. delivery) the mixed bone cement directly through the nozzle 152without the use of the elongated tube 154.

[0077] In any event, once the nozzle assembly 150 has been secured tothe canister 12, the lower end 24 of the cartridge 18 is unscrewed fromthe base 34 thereby separating the canister 12 from the base 34. Suchremoval of the base 34 also exposes a bottom surface 156 of the plunger110 (see FIG. 7). The canister 12 may then be placed in the chamber of adelivery gun mechanism (not shown) much in the same way as a tube ofcaulk is placed in a household caulk gun. As the operator squeezes thetrigger (not shown) or otherwise actuates the gun mechanism, a contactmember (not shown) urges the plunger 110 in the general direction towardthe nozzle assembly 150. Such movement of the plunger 110 forces themixed bone cement within the mixing chamber 14 through the openingsdefined in the blade wiping diaphragm 134 (i.e. the vane receiving slots136 and the shaft receiving opening 138) and then through the nozzle 152and tube 154 of the nozzle assembly.

Operation of the Present Invention

[0078] In operation, the bone cement mixing device 10 of the presentinvention is utilized to mix a liquid bone cement component with apowder bone cement component and thereafter deliver the mixed bonecement to a desired location during performance of a surgical procedure.In order to do so, the powder bone cement component is first placed inthe mixing chamber 14 of the canister 12. In particular, with the mixinghead assembly 30 removed from the canister 12, a quantity of the powderbone cement component is poured or otherwise advanced into the open endof the cartridge 16 (i.e. the upper end 20 of the cartridge 16) andhence into the mixing chamber 14 of the canister 12. As discussed above,the canister 12 is preferably configured to accommodate (i.e. hold) atleast 120 grams (e.g. three batches of 40 grams each) of powder bonecement.

[0079] Once the powder bone cement component has been placed in thecanister 12, the mixing head 30 is screwed onto the upper end 20 of thecartridge 16. In particular, as shown in FIG. 7, the threads 28 of thelower gear housing 38 are threadingly advanced onto the threads 22 ofthe upper end 20 of the cartridge 16 until the mixing head 30 is fullysecured to the canister 12. As discussed above, as the mixing headassembly is screwed onto the upper end of the cartridge 16, the O-ring158 is compressed thereby sealing the mixing head 30 to the canister 12(see FIG. 19).

[0080] Moreover, during such attachment of the mixing head 30 to thecanister 12, the blade wiping diaphragm 134 (which is secured to thewings 144 of the mixing blade 52) is secured to the canister 12. Inparticular, as the mixing head assembly 30 is screwed onto the canister12, the outer peripheral edge 142 of the blade wiping diaphragm 134 ispressed or otherwise advanced under the snaps 140 of the cartridge 16thereby securing the diaphragm 134 to the cartridge 16.

[0081] Once the mixing head assembly 30 is sealingly secured to thecanister 12 in such a manner, the liquid bone cement component (e.g. themonomer) may be advanced into the mixing chamber 12 and hence intocontact with the powder bone cement component positioned therein. Inparticular, as shown in FIG. 7, the port cap 128 is first removed fromsealing engagement with the monomer delivery port 122 in order to permitfluid access to the mixing chamber 14 of the canister 12. Thereafter,the required quantity of liquid cement component may be introduced intothe mixing chamber 14 of the canister 12 through the delivery port 122.Specifically, an outlet coupling of a monomer delivery device (notshown) is first sealingly coupled to the monomer delivery port 122 ofthe mixing device 10. Thereafter, the liquid cement component (e.g. themonomer) contained in the monomer delivery device is introduced into themixing chamber 14 via the fluid path which includes the delivery port122, the tube 124, the fluid passageway 118 of the shaft 104, and thefluid orifices 120 of the shaft 104. In such a manner, the monomer isdelivered at various locations throughout the depth of the powdercomponent present in the mixing chamber 14. In particular, since fluidorifices 120 are provided at a number of different locations along thelength of the shaft 104, the liquid component (e.g. the monomer) isdelivered at locations throughout the height of the canister 12 therebyallowing the liquid to be interspersed throughout the depth of thepowder component present in the mixing chamber 12.

[0082] It should be appreciated that since the monomer delivery port 122is preferably embodied as a luer lock or other type of sealablecomponent, and therefore “mated” with a similar type of outlet couplingon the monomer delivery device, the monomer is dispensed into the tube124 (and hence the mixing chamber 14 of the canister 12) whilepreventing monomer vapors from escaping between the monomer deliverydevice and the mixing device 10 (e.g. between luer of the monomerdelivery device and the luer lock of the mixing device 10).

[0083] It should be appreciated that, as described above, it may bedesirable to introduce the monomer into the mixing chamber 14 of thecanister 12 in the presence of a vacuum within chamber 14. In such acase, a vacuum source (not shown) is fluidly coupled to the vacuum port132 of the lower gear housing 38 of the mixing head assembly 30 in orderto draw air from the mixing chamber 14 of the mixing device 10. Theintroduction of a vacuum is useful during the aforedescribedintroduction of the liquid cement component into the mixing chamber 14since the presence of lower pressure within the chamber 14 tends to drawthe liquid (i.e. the monomer) through the fluid orifices 120 of theshaft 104 and into the mixing chamber 14. Moreover, the presence of thevacuum also removes vapors and the like from the mixing device 10thereby further reducing the occasions in which such vapors escape fromthe device 10. However, in certain applications, it may be desirable tointroduce the liquid monomer into the mixing chamber 14 without thepresence of a vacuum within the canister 12.

[0084] In any event, after the monomer has been dispensed into mixingchamber 14 in the manner described above, the cap 128 is positioned backin sealing engagement within the delivery port 122 so as to prevent theescape of any vapors associated with the delivered monomer. Thereafter,the operator may commence to mix the liquid cement component and thepowder cement component with one another.

[0085] Specifically, the operator grips the outer surface of thecanister 12 with one hand while gripping the knob 44 of the crank 40with the other hand. The operator then rotates the crank 40 in either aclockwise or counterclockwise direction. Such rotation of the crank 40drives the gear train 46 of the mixing head assembly 30. As described indetail above, the gear train 46 of the present invention is configuredsuch that the direction of rotation of the output pinion 48 (and hencethe mixing blade 52) alternates (i.e. changes) despite rotation of thecrank 40 (and hence the directional gear 54) in only a single direction.Specifically, as shown in FIGS. 12-17, as the idler gear 56 is engagedwith the outer gear teeth 90 of the directional gear 54, the outputpinion 48 and hence the mixing blade 52 is rotated in a first direction.However, as the idler gear disengages the outer gear teeth 90 andengages the inner gear teeth 86 of the directional gear 54, thedirection of travel of the output pinion 48 and hence the mixing blade52 is reversed thereby creating alternating or reciprocating motion.

[0086] Moreover, as described above in greater detail, since therelatively large number of individual gear teeth associated with theouter gear teeth 90 creates a relatively large gear ratio with the idlergear 56 relative to the gear ratio created by inner gear teeth 86 andthe idler gear 56, varying angular distances of travel and speeds of themixing blade 52 are created. For example, in the case of the exemplaryembodiment described herein, as the operator advances the crank 40through an entire revolution (i.e. 360° of rotation), the mixing blade52 is driven across 540° of rotation in a first direction and thenreversed and driven across 135° of rotation in the opposite direction.Moreover, in such an exemplary embodiment, when as the operator advancesthe crank 40 through such an entire revolution (i.e. 360° of rotation),the mixing blade 52 is driven three times as quickly in the firstdirection as it is when reversed and driven in the opposite direction.Such a reciprocating movement of the mixing blade 52 (i.e. at varyingangular distances and speeds) creates desirable “agitation” within themixing chamber 14 of the canister 12 which increases the mix quality ofthe mixing device 10 by reducing, if not eliminating, the amount of thepowder component bone cement which is not thoroughly mixed with theliquid component of the bone cement.

[0087] Moreover, as described above in greater detail, during suchmovement (i.e. rotation) of the mixing blade 52, the blade wipingdiaphragm 134 is likewise rotated. In particular, in order to providefor proper alignment of the vanes 116 of the mixing blade 52 with thevane receiving slots 136 of the blade wiping diaphragm 134 duringsubsequent removal of the mixing head assembly 30 from the canister 12,the blade wiping diaphragm 134 is rotatable relative to the cartridge16. Specifically, as show in FIG. 18, the outer peripheral edge 142 ofthe blade wiping diaphragm 134 is positioned under the snaps 140 inorder to secure the diaphragm 134 to the cartridge 16 in a manner whichallows the diaphragm to rotate relative to the cartridge 16. The wings144 of the mixing blade 52 are positioned in the vane receiving slots136 thereby causing the blade wiping diaphragm 134 to be rotated inconcert with the mixing blade 52.

[0088] Once the liquid bone cement component (e.g. the monomer) and thepowder bone cement component have been thoroughly mixed with oneanother, the mixing head assembly 30 is removed from the canister 12. Inparticular, the lower gear housing 38 is unscrewed from the cartridge 16so that the mixing head assembly 30 may be removed from the cartridge 16thereby allowing the delivery nozzle assembly 150 (see FIGS. 23 and 24)to be screwed onto the cartridge 16 in its place. During such removal ofthe mixing head assembly 30, as shown in FIG. 19, the vanes 116 of themixing blade 52 are advanced through the vane receiving slots 136 of theblade wiping diaphragm 134. In particular, since the blade wipingdiaphragm 134 is secured to the cartridge 16 by the snaps 140, themixing blade 52 may be “pulled through” the openings (i.e. the vanereceiving slots 136 and the shaft receiving opening 138) defined in theblade wiping diaphragm 134 without removing the blade wiping device.Such advancement of the vanes 116 through the vane receiving slots 136wipes or otherwise removes any residual bone cement from the vanes 116thereby preventing such residual bone cement from being wasted (i.e.removed from the mixing chamber 14, but not utilized in the surgicalprocedure).

[0089] The mixing device 10 of the present invention may be utilized todeliver the mixed bone cement. In particular, as shown in FIGS. 23-25,once the liquid bone cement component (e.g. the monomer) and the powderbone cement component have been thoroughly mixed with one another, thelower gear housing 38 is unscrewed from the cartridge 16 so that themixing head assembly 30 may be removed from the cartridge 16.Thereafter, the delivery nozzle assembly 150 is screwed onto the threads22 of the upper end 20 of the cartridge 16. The lower end 24 of thecartridge 18 is then unscrewed from the base 34 thereby separating thecanister 12 from the base 34. As described above and shown in FIG. 7,such removal of the base 34 also exposes the bottom surface 156 of theplunger 110. The canister 12 may then be placed in the chamber of adelivery gun mechanism (not shown) much in the same way as a tube ofcaulk is placed in a household caulk gun. As the operator squeezes thetrigger (not shown) or otherwise actuates the gun mechanism, a contactmember (not shown) urges the plunger 110 in the general direction towardthe nozzle assembly 150. Such movement of the plunger 110 forces themixed bone cement within the mixing chamber 14 through the openingsdefined in the blade wiping diaphragm 134 (i.e. the vane receiving slots136 and the shaft receiving opening 138) and then through the nozzle 152and tube 154 of the nozzle assembly 150 thereby delivering the mixedbone cement to a desired location.

[0090] Hence, as described herein, bone cement mixing device 10 of thepresent invention provide numerous advantages over heretofore designedmixing apparatus. For example, the alternating or reciprocating actionof the mixing blade 52 enhances the quality of the mixed bone cement byreducing, if not eliminating, the amount of powder component which isnot adequately mixed with the liquid component. Moreover, suchalternating or reciprocating action is advantageously generated byrotation of the crank 40 in only a single direction and at a singlespeed. In particular, the configuration of the gear train 46 eliminatesthe need for the operator to manually reverse the direction of the crank40 and/or manually alter the speed at which the crank 40 is beingrotated in order to produce the desired blade movement.

[0091] Yet further, the sealed relationship between the outlet couplingof the monomer delivery device and the delivery port 122 of the mixingdevice 10 provides for delivery and mixing of the bone cement withoutexposing the operator of the system to monomer vapors.

[0092] In addition, since the fluid orifices 120 of the mixing blade 52are provided at a number of different locations along the length of theshaft 104, the liquid component (e.g. the monomer) is delivered atlocations throughout the height of the canister 12 thereby allowing theliquid to be interspersed throughout the entire depth of the powdercomponent present in the mixing chamber 12. As described above, this isa significant advantage over heretofore designed systems in which themonomer is poured or otherwise advanced through the lid of the mixingapparatus thereby only allowing the monomer to be introduced to the“top” of the powder within the mixing apparatus. Moreover, the structureof the present invention also provide advantages over heretoforedesigned system having a delivery path through the mixing shaft of thesystem which have an opening only at the bottom end of the shaft(similar to a common drinking straw). In such a configuration, themonomer only flows out of the bottom of the shaft and in some cases maybe restricted by the plunger on which the lower end of the shaft rests.

[0093] While the invention has been illustrated and described in detailin the drawings and foregoing description, such an illustration anddescription is to be considered as exemplary and not restrictive incharacter, it being understood that only the preferred embodiments havebeen shown and described and that all changes and modifications thatcome within the spirit of the invention are desired to be protected.

[0094] There are a plurality of advantages of the present inventionarising from the various features of the bone cement mixing and deliverydevice and associated method described herein. It will be noted thatalternative embodiments of the bone cement mixing and delivery deviceand associated method of the present invention may not include all ofthe features described yet still benefit from at least some of theadvantages of such features. Those of ordinary skill in the art mayreadily devise their own implementations of a bone cement mixing anddelivery device and associated method that incorporate one or more ofthe features of the present invention and fall within the spirit andscope of the present invention.

What is claimed is:
 1. A bone cement mixing apparatus, comprising: ahandle; a canister defining a mixing chamber; and a mixing blade whichis caused to rotate in response to movement of said handle, said mixingblade being positioned within said mixing chamber, wherein said mixingblade includes a shaft and at least one vane supported by said shaft,and wherein said shaft has defined therein (i) an inlet orifice, (ii) aplurality of outlet orifices, and (iii) a passageway which places saidinlet orifice in fluid communication with each of said plurality ofoutlet orifices.
 2. The bone cement mixing apparatus of claim 1,wherein: said shaft has an upper half segment and a lower half shaftsegment, and at least one of said plurality of outlet orifices isdefined in said upper half segment.
 3. The bone cement mixing apparatusof claim 1, wherein: said shaft has an upper half segment and a lowerhalf shaft segment, at least a first pair of said plurality of outletorifices is defined in said upper half segment, and at least a secondpair of said plurality of outlet orifices is defined in said lower halfsegment.
 4. The bone cement mixing apparatus of claim 3, wherein: eachof said first pair of said plurality of outlet orifices is verticallyspaced apart from each other along the length of said shaft, and each ofsaid second pair of said plurality of outlet orifices is verticallyspaced apart from each other along the length of said shaft.
 5. The bonecement mixing apparatus of claim 1, wherein: said shaft has a distalend, and at least one of said plurality of outlet orifices is spacedapart from said distal end of said shaft.
 6. The bone cement mixingapparatus of claim 1, wherein: said plurality of outlet orificesincludes at least seven outlet orifices, and each outlet orifice of saidat least seven outlet orifices is vertically spaced apart from eachother along the length of said shaft.
 7. The bone cement mixingapparatus of claim 1, further comprising: a gear assembly having aplurality of mixing gears which are caused to rotate in response tomovement of said handle, said mixing blade being caused to rotate inresponse to rotation of said mixing gears of said gear assembly; a fluidtube which extends through said gear assembly, said fluid tube being influid communication with said inlet orifice of said shaft.
 8. The bonecement mixing apparatus of claim 7, wherein: said handle has a fluiddelivery port defined therein, and said fluid tube is in fluidcommunication with said fluid delivery port.
 9. The bone cement mixingapparatus of claim 7, wherein said tube extends through at least one ofsaid plurality of mixing gears.
 10. A method of mixing bone cement,comprising the steps of: placing a powder bone cement component within acanister; sealing the canister after the placing step; advancing aliquid bone cement component through a mixing blade located within thecanister after the sealing step; and rotating the mixing blade after theliquid bone cement component is advanced through the mixing blade,wherein the mixing blade includes (i) an inlet orifice, (ii) a pluralityof outlet orifices, and (iii) a passageway which places the inletorifice in fluid communication with each of the plurality of outletorifices, and wherein the advancing step includes the step of advancingthe liquid bone cement component (i) into the mixing blade through theinlet orifice, (ii) through the passageway, and (iii) out of the mixingblade through the plurality of outlet orifices.
 11. The method of claim10, wherein: said mixing blade has an upper half portion and a lowerhalf shaft portion, and at least one of said plurality of outletorifices is defined in said upper half portion.
 12. The method of claimof claim 10, wherein: said mixing blade has an upper half portion and alower half portion, at least a first pair of said plurality of outletorifices is defined in said upper half portion, and at least a secondpair of said plurality of outlet orifices is defined in said lower halfportion.
 13. The method of claim of claim 12, wherein: each of saidfirst pair of said plurality of outlet orifices is vertically spacedapart from each other, and each of said second pair of said plurality ofoutlet orifices is vertically spaced apart from each.
 14. The method ofclaim 10, wherein: said mixing blade includes a shaft having a distalend, and at least one of said plurality of outlet orifices is spacedapart from said distal end of said shaft.
 15. The method of claim 10,wherein: said plurality of outlet orifices includes at least sevenoutlet orifices, and each outlet orifice of said at least seven outletorifices is vertically spaced apart from each other along the length ofsaid shaft.
 16. The method of claim 10, wherein the rotating stepincludes the steps of (i) moving a handle so as to rotate a plurality ofmixing gears of a gear assembly, and (ii) rotating said mixing blade inresponse to rotation of said plurality of mixing gears of said gearassembly, further comprising the step of: advancing said liquid bonecement component through said gear assembly to said inlet orifice ofsaid mixing blade.
 17. The method of claim 16, wherein the step ofadvancing said liquid bone cement component through said gear assemblyto said inlet orifice of said mixing blade includes the step ofadvancing said liquid bone cement component through a channel defined inat least one of said plurality of mixing gears of said gear assembly.18. A bone cement mixing apparatus, comprising: a container defining amixing chamber; and a mixing blade positioned within said mixingchamber, said mixing blade defining (i) an inlet orifice, (ii) aplurality of outlet orifices, and (iii) a passageway which places saidinlet orifice in fluid communication with each of said plurality ofoutlet orifices.
 19. The bone cement mixing apparatus of claim 18,wherein: said mixing blade has an upper half portion and a lower halfportion, and at least one of said plurality of outlet orifices isdefined in said upper half portion.
 20. The bone cement mixing apparatusof claim 18, wherein: said mixing blade has an upper half portion and alower half portion, at least two of said plurality of outlet orificesare defined in said upper half portion and vertically spaced apart fromeach other, and at least another two of said plurality of outletorifices are defined in said lower half portion and vertically spacedapart from each other.
 21. The bone cement mixing apparatus of claim 18,wherein: said mixing blade includes a shaft having a distal end, and atleast one of said plurality of outlet orifices is spaced apart from saiddistal end of said shaft.
 22. The bone cement mixing apparatus of claim18, wherein: said plurality of outlet orifices includes at least sevenoutlet orifices, and each outlet orifice of said at least seven outletorifices is vertically spaced apart from each other.
 23. The bone cementmixing apparatus of claim 18, further comprising: a gear assembly havingan output gear mechanically coupled to said mixing blade; and a fluidtube which extends through said gear assembly, said fluid tube being influid communication with said inlet orifice of said mixing blade. 24.The bone cement mixing apparatus of claim 23, further comprising ahandle mechanically coupled to an input gear of said gear assembly,wherein: said handle has a fluid delivery port defined therein, and saidfluid tube is in fluid communication with said fluid delivery port. 25.The bone cement mixing apparatus of claim 18, further comprising: a gearassembly having a plurality of mixing gears which cooperate with eachother to transmit force to said mixing blade; and a fluid tube which (i)is in fluid communication with said inlet orifice of said mixing blade,and (ii) extends through at least one of said plurality of mixing gears.26. A bone cement mixing apparatus, comprising: a handle; a firstcanister segment defining a first mixing chamber portion; a secondcanister segment defining a second mixing chamber portion; and a mixingblade which is caused to rotate in response to movement of said handle,wherein said mixing blade is located within both said first mixingchamber portion and said second mixing chamber portion, wherein saidfirst canister segment includes a first coupling, wherein said secondcanister segment includes a second coupling, and wherein said firstcoupling cooperates with said second coupling so as to secure said firstcanister segment to said second canister segment.
 27. The bone cementmixing apparatus of claim 26, wherein: said first coupling includes afirst threaded portion, and said second coupling includes a secondthreaded portion.
 28. The bone cement mixing apparatus of claim 27,wherein: said first threaded portion includes an internally threadedportion, and said second threaded portion includes an externallythreaded portion.
 29. The bone cement mixing apparatus of claim 26,wherein said first canister segment possesses the same configuration assaid second canister segment.